Page 274 - Beginning PHP 5.3

Part III: Using PHP in Practice
However, it ’ s generally a good idea to write your code so that it doesn ’ t generate notices. This helps to
ensure the robustness and security of your application. This means that you should check for the
presence of a submitted form field before using it, rather than assuming that it exists. You can do this
using PHP functions such as isset() or array_key_exists() :

<dt>Gender</dt><dd><?php if ( isset( $_POST["gender"] ) ) echo $_
POST["gender"]?></dd>

Dealing with Multi - Value Fields

You learned earlier in the chapter that you can create form fields that send multiple values, rather than a
single value. For example, the following form fields are capable of sending multiple values to the server:

<label for=”favoriteWidgets”>What are your favorite widgets?</label>
<select name=”favoriteWidgets” id=”favoriteWidgets” size=”3”
multiple=”multiple”>
<option value=”superWidget”>The SuperWidget</option>
<option value=”megaWidget”>The MegaWidget</option>
<option value=”wonderWidget”>The WonderWidget</option>
</select>
<label for=”newsletterWidgetTimes”>Do you want to receive our
‘Widget Times’ newsletter?</label>
<input type=”checkbox” name=”newsletter” id=”newsletterWidgetTimes”
value=”widgetTimes” />
<label for=”newsletterFunWithWidgets”>Do you want to receive our
‘Fun with Widgets’ newsletter?</label>
<input type=”checkbox” name=”newsletter” id=”newsletterFunWithWidgets”
value=”funWithWidgets” />
The first form field is a multi - select list box, allowing the user to pick one or more (or no) options. The
second two form fields are checkboxes with the same name ( newsletter ) but different values
( widgetTimes and funWithWidgets ). If the user checks both checkboxes then both values,
widgetTimes and funWithWidgets , are sent to the server under the newsletter field name.

So how can you handle multi - value fields in your PHP scripts? The trick is to add square brackets ( [] )
after the field name in your HTML form. Then, when the PHP engine sees a submitted form field name
with square brackets at the end, it creates a nested array of values within the $_GET or $_POST (and
$_REQUEST ) superglobal array, rather than a single value. You can then pull the individual values out of
that nested array. So you might create a multi - select list control as follows:

< select name=”favoriteWidgets[]” id=”favoriteWidgets” size=”3”

multiple=”multiple” ... < /select >
You ’ d then retrieve the array containing the submitted field values as follows:
$favoriteWidgetValuesArray = $_GET[“favoriteWidgets”]; // If using get method

$favoriteWidgetValuesArray = $_POST[“favoriteWidgets”]; // If using post method

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